Digital content such as electronic books (“eBooks”) have undergone tremendous growth. Devices such as eBook readers and ubiquitous smart phones bring reading content to large numbers of users, and many users have transitioned nearly entirely away from paper-based reading content.
In achieving this level of popularity, existing devices and technologies have largely concentrated on replicating the look and feel of traditional paper-based books and magazines. However, electronic viewing and communications technologies open new possibilities for enhancing text-based content and for adding functionality and supplemental information to the content itself.